CT scan for chronic sinus infections?

I always prone to catch cold, sinus infection, strep throat often. I used to get one infection in 2 or 3 months. Always resolve with antibiotics. Catch cold if I go out in cold weather, cold wind and if I have ice cream or cold good items. I never tested for any allergies.i an in USA now.had one pns x-ray when I was in India last year. Here, ENT told me to get CT scan and x-ray to check if I have any infection. I have sinus infection, ear infection, swelling under ear for past 3 weeks.was on amoxicillin and it didn't reduce the pain and swelling. Went to an ENT and he did an Endo and said no infection in the sinus now and no infection in ear. He put me on another antibiotic for 2 weeks to see if the jaw swelling and ear pain is secondary infection. He told me to get imaging fine after 2 weeks. Is CT scan really necessary even if there's is no sinus infection now? ENT is not sure why I have the jaw pain,ear pain, swelling under ear. Just told me to get an x-ray and CT scan done. Help.